Safranine dyestuff intermediates and process of preparing the same



Patented Nov. 14, 1933 SAFRANI'NE DYESTUFF INTERMl'iD IATES 'VANDIPRYOCESS or PREPARING THE SAME,

Walter o. Meuly, Milwaukee, Wis, assignor, by

mesne assignments, to E. I. du Pont de Ne-, mom's, & Company, a corporation of Delaware No Drawing. Original application February 26, 1930, Serial No. 431,637. Divided and this 3111-! plication-July 3, 1931. Serial No. 548,703

' 9Claims. (01. 260-129) by oxidizing diphenyl-1,3-naphthylene-diamine-- 8-sulphonio acid with various para-diamines of the group generally known as Nerol acids. For example, U. S. Patent No. 940,354describes various dyestuffs of this type among which may be mentioned that prepared by the joint oxidation of said naphthylene-diamine and para-aminoortho-methoXy-amino-diphenyl-amine-sulphonic'acid. Other para-diamine sulphonicacids are also described in said patent. The colors resulting from the use of these dyes are blue or reddish blue.

As described in my copending application referred to, I have found that by substituting for the para-diamine-sulphonic acids mentioned in U. S. Patent 940,354, the following, namely: 4-amino-2- methoxy-5- methyl diphenylamine sulphonic acid, a dyestuif is produced which dyes in-greenishblue' shades of excellent fastness to light and to washing. This novel dyestuif is exceptionally valuable for dyeing both wool and silk. Its fastness qualities are materially superior to those of the dyestuff obtained by using, as the para-diamine, para-amino-diphenylamineortho-sulfonic acid.

The intermediates which I use in the production of the novel dyestuffs are in themselves novel products and form the subject matter of this application. These intermediates may be prepared by condensing cresidine with paranitro-chloro-benzene-ortho-sulfonio acid in the presence of an alkaline reacting substance .and reducing the resulting condensation product to its corresponding amine.

It is accordingly, an object of this invention to provide new intermediates for use in preparing a dyestuff of the sairanine series which is extremely fast to light and washing.

It is a further object of this invention to prepare novel dyestuii intermediatesby'condensing cresidine with para-nitro-chloro-benzeneortho-sulfonic acid and reducingthe condensation product to the corresponding amine.

Other and further important objects of this invention will become apparent from the-following description and appended claims. 1

The following examples in: which. parts by weight are given serve to illustrate the methods of preparing the novel dyestuff intermediates according to my invention. 7,

Example 1 v until it reacts acid to Congo red paper. After cooling the reaction mass to room temperature, the end product may, be isolated in the form of an orange yellowcrystalline" masshaving a constitution probably correspondingto the follow- I ing formula:

503K 0 CH i I If desired, this product which is 4-nitro-2'- methoxy-5-methyl-diphenylamine sulfonic acid,

may be reduced directly to the amine in the wellknown manner.

Example 2 water and 28 parts of 20 B. hydrochloric acid.

The mixture is maintained at a temperature of 90 to C. When the reduction is complete, as

shown by a test sample, the iron is precipitated acid most probably the following chemical constitution:

SOQH OOHs densation product to its corresponding amine.

I HaN N It is, of course, to be understood, that while I have disclosed the preferred embodiment of my invention, various details of my disclosure may be varied and, accordingly, I do not propose to limit my invention except as necessitated by the prior art.

It should also be understood that the utility of my novel products is general and is not lim-.

ited to the preparation of safranine dyestuffs. For example, the new products may be used in the synthesis of azo typedyestuifs.

I claim as my invention:

1. A compound having most probably the following chemical constitution:

OzN

2. A dyestufi intermediate having in the form of its free acid most probably the following chemical constitution:

said intermediate being obtainable'by condensing cresidine with para-nitro-chloro-benzeneortho-sulphonic acid ln'the presence of an alkaline reacting agent.

3. A compound having in the form of its free approximately 180 C.

4. The process of preparing a dyestuff intermediate which comprises condensing cresidine with para-nitro-chloro-benzene-ortho-sulphonic acid in the presenceof an alkaline reacting substance.

5. The processor preparing a dyestufif inter-' mediate which comprises condensing cresidine with para-nitro-chloro-benzene-ortho-su1phonic acid in the presence of an alkaline reacting substance under pressure and at a temperature of 6, The process of preparing a dyestufi intermediatewhich comprises condensing cresidine with para-nitro-chloro-benzene-ortho-sulphonic acid in the presence of an alkaline reacting substance and reducing the resulting condensation product to its corresponding amine.

'7. The process of preparing a dyestufi intermediate which comprises condensing cresidine with para-nitro-chloro-benzene-ortho-sulphonic acid in the presenceof sodium bicarbonate and treating the resulting condensation product with a mixture of iron powder and hydrochloric acid to reduce the same to its correspinding amine.

8. The process of preparing a dyestuif intermediate which comprises heating 4-nitro-2'- methoxy-fi-methyl-diphenylamine sulfonic acid with powdered iron and hydrochloric acid to thereby reduce said nitro body to its corresponding amine.

9. Compounds having most probably lowing chemical constitution:

the fOl- 

